Communication signal lamp control circuit



TELEGRAPH LINE) REPEA 75/? B. OSTENDORF, JR.. ET AL COMMUNICATION SIGNAL LAMP CONTROL CIRCUIT Filed July 19, 1951 REcE/VEMT/VE REPEATER HUB TELEGRAPH REPEATER & COUPLING UNIT B. 05 TENDORF, JR R. A. VANDERL lPPE ATTOR EV INVENTORS 'Patented Oct. 27, 1953 COMMUNICATION SIGNAL LAMP CONTROL CIRCUIT Bernard Ostendorf, Jr., Stamford, Conn., and

Richard A. Vanderlippe, Bloomfield, N. .L, assignors to Bell Telephone Laboratories, Incorporated, New York, N

York

. Y., a corporation of New Application July 19, 1951, Serial No. 237,506

6 Claims.

This invention is an improved control circuit for a space discharge device. More specifically it is an improved signaling circuit wherein a space discharge device, such as an inert gas lamp is employed as a signal. this invention is an improved idle indicating circuit such as is employed, for instance, in cooperation with communication circuits to indicate idle circuits available at the moment for selection by an operator.

An object of the invention is the improvement of control circuits for space discharge devices. A more specific object is the improvement of signaling circuits, such as idle indicating circuits, in which a space discharge lamp, such as an inert gas lamp, is employed as a signal.

There are a number of advantages to be had in the employment of space discharge lamps, such as neon or other inert gas lamps, as signals in various signaling circuits, particularly in idle indicating circuits, employed, for instance, to indicate, to operators at manual switchboards, cir cuits which are available at the moment for selection as communication paths to distant cities. Among these advantages are that they are relatively inexpensive in first cost, have a longer life and are low in current consumption. This latter factor is of considerable importance. As is well understood, current drain on the battery of a communication oiiice is a factor which is evaluated closely against the service thereby afforded. The advantage of speed in operation afforded by a substantially instantaneous indication of all circuits presently available in the switchboard to a particular destination, by means of an idle indicating circuit, which, for instance, lights a lamp associated individually with each idle circuit for an interval, must be weighed against a method of testing each trunk individually in succession by means of thewell-known busy test or by other methods, which methods are not quite so fast or convenient. One of the important factors in the comparison is the current drain of the required lamps and the matter of such drain at times of commercial power service failure when all of the communication circuits in the ofiice are required to be supplied from the emergency or standby battery may be critical.

There are difficulties inherent in the employment of lamps such as neon lamps in signaling. The chief of these is their tendency to flicker. A signal lamp to be satisfactory in communication service must afford a positive indication of the condition which it is its function to indicate. If, for instance, a lighted lamp indicates avail- Yet more specifically able circuits and a non-lighted lamp the opposite, a lamp which flickers momentarily when it should extinguish is unsuitable for the purpose.

At telephone and telegraph trunk boards as well as at telegraph service boards wherein, for instance, there may be many positions in the same line-up of switchboards, two operators at New York, for instance, may require a circuit to Chicago at substantially the same moment. Each presses the idle indicating key at her position. A number of lamps, ten for instance, individually associated with each idle circuit to Chicago light at the two positions. There will inevitably be a certain few double connections due to simultaneous selection, say in the same hundredth of a second, of the same idle circuit by two operators at dilferent positions. This is assuming the usual incandescent type lamp. The number of double connections has been very materially increased, however, when lamps, such as neon or other inert gas lamps, have been tried in service to perform this function, because of flicker or persistence of illumination after disconnection of power. Therefore, notwithstanding their desirability from other standpoints, it has not been possible to employ such lamps in such service.

The present invention overcomes this difficulty and it may be understood from a consideration of the following description when read with ref erence to the associated drawing which, taken together, disclose a preferred embodiment in which the invention is presently incorporated although it is to be understood that the inven tion may be incorporated in other embodiments which will be readily suggested to those skilled in the art by the following:

In the drawing, a telegraph channel l, which connects to a distant station, is shown connected through a telegraph line repeater 2 and hub telegraph repeater coupling unit 3, both well known in the art, receiving leg 4 and sending leg 5, contacts a and 0, respectively, of relay Kl, when relay Kl is released as shown, and hub jack circuit 6, also well known in the art, to receiving hub RH and sending hub SH, respectively. The hubs are connected to the blades of a doublepole, double-throw switch SW by means of which I they may be interconnected, when the switch is in a first position, through the hub link HL to form a single electrical point or hub, or, when the switch is in a second position, through the regenerative repeater, in Which case a delay is interposed between the reception of an incoming ated. Thisextends the battery supply circuit from conductor through contact b of relay K2, resistor R1 and the top and bottom windings of relay K3 to negative battery [6. The windings of relay K3are shuntedby condenser C2 which together" with resistor R! constitute a delay circuit whichdelays the operation of relay K3 for an interval such as ten milliseconds after which the battery supply circuit is extended through the contact of relay K3 and inductance LI and resistor RI! in parallel to the right-hand terminal of inert gas idle indicating lamp IL. Depending on whether the circuit I is busy or idle direct ground through contact e of relay Kl, or negative battery through the left-hand winding and contact I of relay Kl, respectively, will be connected through armature 22 of relay KI and resistor Rla to the left-hand terminal of lamp IL. If the line I is connected into its normally assigned hub concentration, relay K! is released and armature 22 is connected through contact e of relay Kl to ground. Lamp IL which for this example has an ionizing potential greater than 55 volts, does not light for this condition. If line I has been released from its normal assignment by operation of relay K! on its right-hand winding as previously explained, armature 22 is connected through contact 1 of relay KI and the left hand winding of relay Kl to negative 48-volt battery. For this condition the potential across lamp IL is the arithmetic sum of the 48-volt battery and the potential appearing on lead 25; hence lamp IL will be lighted whenever relay K3 is operated or relay K2 is unoperated. Once operated, relay K3 will remain operated during the remainder of the quarter-second interval while relay K2 remains operated. After ground is disconnected by the interrupter and relay K2 starts to release, relay K3 will hold for an interval at least as long as required for the transition of the armature of relay K2 from its contact b to its contact 11. Then the supply circuit will be extended through contact a of relay K2 for one-quarter second per cycle.

The net result of the operation of relays K2 and K3 is that in each half-second cycle of interrupter INT the positive 55-volt rectifier supply is disconnected from the right-hand terminal of lamp IL for a predetermined short interval, such as for ten milliseconds, as determined by the constants of the delay circuit, resistor R1 and capacitance C2. The operation of idle lamp indicator key IL! efiects the connection of a directcurrent potential of positive 55-volts through conductor 2%}- f-or an interval of nine seconds duration as heretofore explained. This supply is interrupted for ten milliseconds every half second during the interval while relay K2 is operated to open contact a and before relay K3 is operated to close its contact. If circuit 1 is idle and is selected by an operator at some switchboard position, in response to the lighting of its lamp IL at any position, the operator inserts plug PI of the patching cord PC into jack LM of circuit l and patches plug P2 of cord PC to the jack T of a line forming part of the particular concentration group to which line I is to be joined. A low resistance ground through resistor R25 on the sleeve of the PI plug of patching cord PC reduces the potential of the lefthand terminal of lamp IL to near zero. If lamp IL has a sustaining potential requirement of more than the 55 volts assumed for this example it will be extinguished immediately upon connection of plug Pl to jack LM. If. however, due to aging of the lamp or any other reason the sustaining potential exceeds 55 volts, the lamp will be ex-' tinguished when the potential of lead 25 is reduced to zero for the short interval previously described; thus the accuracy of the idle indication is not restricted by variations in the sustaining potential of the indicator lamp IL.

A second purpose of the ground applied through resistance R25 to the sleeve of the LM jack is to complete a circuit path which may be traced from battery on the left winding of relay Kl through contacts 1 of relay KI, the sleeve of jack LM and resistor R25 to ground. Current flowing in this path will hold relay Kl operated even though plug P is removed from jack T. This arrangement prevents the inadvertent disconnection of circuit I from its assignment by way of patch cord PC to another concentration group.

It has been found that the eifect of the opening of the lamp circuit for a period of 10 milliseconds every half second cannot be observed visually. However, it insures the rapid extinction of lamp IL when the circuit is seized and thus prevents flicker and double connections.

What is claimed is:

1. A space discharge device, a battery supply circuit connected to said device to light said device for a first interval as a signal, an interrupter in said battery supply circuit and a timing circuit control connected to said interrupter for interrupting said supply for a second interval during said first interval, said second interval shorter in duration than is manifest visually to minimize flicker.

2. A space discharge lamp, a battery supply connected thereto to light said lamp, an interrupter in said supply, said interrupter having a control and timing means therefor actuable to interrupt said supply for an interval shorter in duration than is observable visually.

3. An inert gas lamp, a battery supply therefor connected thereto, an interrupter in said supply, a first control connected to said interrupter, a first timer connected to said control, a second timer and a second control therefor connected to said battery supply for activating said battery supply for a first interval measurable in seconds, and means responsive to said first timer and said first control for actuating said interrupter to interrupt said supply, during said first interval, for a second interval measurable in milliseconds.

4. An inert gas lamp, a battery supply circuit for said lamp extending through an interrupter and through a contact of a switch controlled by said interrupter to said lamp, said circuit continuous through said interrupter while said interrupter is in a first condition at a first time, said circuit discontinuous while said interrupter is in a second condition at a second time, said circuit continuous through said contact after an interval measurable in milliseconds at a third time, and a delay circuit connected to said switch for preverliting the closure of said contact for said interva 5. An inert gas lamp, a battery supply circuit therefor extending through an interrupter, through a contact of a first switch connected to and actuated by said interrupter and thereafter through a contact of a second switch connected to and operated in response to the operation of said first switch after a predetermined delay 7- 6. idle indicator control circuit havingan oientiy short duration to prevent visual maniinertgas lamp for indicating the condition of festation thereoi said Iampw'heniighfed. circuits available for use, a;- battery supp-1ycii BERNARD OSTENDQBF J R. cuit connected 110 said" lamp; and: means for insur- RICHARD VANDERLIPPE-- ing. the rapid extinction of said lamp and minimi'zingifi-icker to' prevent. double connections, said References Cited in the me of this patent means comprising an interrupter in said battery UNITED STATES PATENTS supply" circuit; andi a centroifor said interrupter Number Name Dan; for interrupting said supply for a predetermined 10 2 0703623 saterlea- Feb. 16,1931? interval of duration during a lighted interval of 2,186,013" Edgerton J'an'. 9', 1940 

